Post-collisional highly potassic magmatism in large orogenic belts has been taken as evidence for recycling of continent-derived K-rich sediments within the orogenic lithospheric mantle. Potassium isotopes may provide important insights into the origins of Kinthesemagmas,sincesubductingsedimentsexhibitmuchmorevariableK isotopic compositions relative to the mantle. Here we report high precision K isotope data for 41 representative potassic and ultra-potassic volcanic rocks from the whole Alpine-Himalayan orogenic belt. δ41KNIST SRM3141a of these samples vary from −1.55 ‰ to −0.32 ‰, comparable to the range of global subducting sediments but significantly exceeding the range of pristine mantle defined by oceanic basalts (−0.42 ±0.08 ‰). Monte Carlo simulation suggests this large K isotopic range can be reproduced by recycling of up to 5 % isotopically heterogeneous sediments into the depleted mantle. Our results highlight K isotopes as a potential tracer of recycled sediments in the mantle.

Wang, Z.-Z., Teng, F.-Z., Prelević, D., Liu, S.-A., Zhao, Z. (2021) Potassium isotope evidence for sediment recycling into the orogenic lithospheric mantle. Geochem. Persp. Let. 18, 43–47.